A lot of people who order their steaks well done will say that ordering medium rare is just a convention people follow to look impressive. I've actually had friends mock me for "being pretentious" and ordering medium rare before. These people often have never even HAD a good medium rare steak. The steaks are more tender, more flavourful, more aromatic, and more visually interesting.
The only real reason not to order it that way is squeamishness. I suppose that can't be helped, but it's worth pointing out that medium rare usually doesn't mean "bloody". It is not, however, a good idea to point out to those people that they're eating dead, murdered animal flesh and should just get over any additional squeamishness.